Clinical evaluation of closed tray impression and intraoral scanning techniques in single posterior tissue-level implant-supported crowns: A self-controlled case study.

STATEMENT OF PROBLEM: Different techniques have been used to record the locations of dental implants, yet research examining the clinical outcomes of posterior implant-supported prostheses generated by different techniques, particularly concerning their fit, is lacking. PURPOSE: The purpose of this self-controlled study was to evaluate the clinical outcomes of closed tray impression making and intraoral scanning for single posterior implant-supported restorations. MATERIAL AND METHODS: Eighty-two participants with a single missing posterior tooth were included. The restorations were delivered a minimum of 3 months after tissue-level implant placement. Each participant was provided with 2 screw-retained monolithic zirconia crowns, produced using 3-dimensional (3D) gel deposition from both closed tray impression making (control group) and intraoral scanning using an iTero scanner (experimental group). The recording operating time, the patient comfort assessed using a visual analog scale (VAS), and the fit of the crowns were recorded during clinical evaluation. The paired t test and Mann-Whitney U test were conducted to statistically analyze the differences between the 2 techniques (α=.05). RESULTS: Seventy-six participants completed the study with a dropout rate of 7.3%. The mean ±standard deviation recording operating time of the control and experimental groups was 683 ±164 and 777 ±407 s, respectively (P<.05). The mean ±standard deviation VAS score of the control and experimental groups was 2.6 ±1.6 and 1.3 ±1.0, respectively (P<.05). The crowns in both groups showed excellent marginal fit (P>.05), but the occlusal contacts of crowns in the experimental group were significantly better (P<.05), while the interproximal contacts were significantly worse (P<.05) compared with those in the control group. In the control group, 1 crown was rated as Delta for occlusal contact and deemed clinically unacceptable. CONCLUSIONS: In single posterior tissue-level implant-supported restorations, the clinical outcomes of most of the screw-retained monolithic zirconia crowns generated from closed tray impression making and intraoral scanning with the iTero system and fabricated by 3D gel deposition were acceptable. Compared with the closed tray impression technique, intraoral scanning resulted in better patient comfort and occlusal contacts but worse interproximal contacts. Efficiency was lower with intraoral scanning.

Relationship of buccolingual inclination between the alveolar bone and first molar in different vertical facial types: A CBCT study.

BACKGROUND: This study aimed to investigate the differences in the buccolingual inclination and transverse width of maxillary and mandibular first molars among different vertical facial types. METHODS: In all, 78 samples were divided into three groups based on the GoGn-SN angle: the low-angle group (n = 26, mean age=24.21±5.11), average-angle group (n = 26, mean age=22.66±3.72), and high-angle group (n = 26, mean age=22.23±2.43). Cone beam computed tomography (CBCT) measurements were used to assess the buccolingual inclination of the axis of the maxillary and mandibular first molars, as well as the buccolingual inclination of the alveolar bone, the dental arch width, and the basal bone width. One-way ANOVA, the LSD test, and Pearson correlation analysis were performed. RESULTS: The high-angle group showed significantly greater lingual inclination of the maxillary alveolar bone than the low-angle group and average-angle group (p < 0.001; p < 0.05). The difference in buccolingual inclination of the axis of the maxillary first molar and the alveolar bone was significantly greater in the high-angle group than in the low-angle group (p < 0.05). Both the maxillary and mandibular dental arch were significantly narrower in the high-angle group than in the other two groups. The mandibular basal bone was also significantly narrower in the high-angle group than in the low-angle group and average-angle group (p < 0.001; p < 0.01). CONCLUSIONS: The alveolar bone of maxillary first molar in the high-angle group was more palatal inclined than that the low-angle group and the average-angle group, which suggests that orthodontists should pay more attention to the root-bone relationship in the high-angle group during expansion treatment to prevent bone fenestration and dehiscense.

Comparison of the Efficacy of Artificial Intelligence-Powered Software in Crown Design: An In Vitro Study.

INTRODUCTION AND AIMS: Artificial intelligence (AI) has been adopted in the field of dental restoration. This study aimed to evaluate the time efficiency and morphological accuracy of crowns designed by two AI-powered software programs in comparison with conventional computer-aided design software. METHODS: A total of 33 clinically adapted posterior crowns were involved in the standard group. AI Automate (AA) and AI Dentbird Crown (AD) used two AI-powered design software programs, while the computer-aided experienced and computer-aided novice employed the Exocad DentalCAD software. Time efficiency between the AI-powered groups and computer-aided groups was evaluated by assessing the elapsed time. Morphological accuracy was assessed by means of three-dimensional geometric calculations, with the root-mean-square error compared against the standard group. Statistical analysis was conducted via the Kruskal-Wallis test (α = 0.05). RESULTS: The time efficiency of the AI-powered groups was significantly higher than that of the computer-aided groups (P < .01). Moreover, the working time for both AA and AD groups was only one-quarter of that for the computer-aided novice group. Four groups significantly differed in morphological accuracy for occlusal and distal surfaces (P < .05). The AD group performed lower accuracy than the other three groups on the occlusal surfaces (P < .001) and the computer-aided experienced group was superior to the AA group in terms of accuracy on the distal surfaces (P = .029). However, morphological accuracy showed no significant difference among the four groups for mesial surfaces and margin lines (P > .05). CONCLUSION: AI-powered software enhanced the efficiency of crown design but failed to excel at morphological accuracy compared with experienced technicians using computer-aided software. AI-powered software requires further research and extensive deep learning to improve the morphological accuracy and stability of the crown design.

Restoration of teeth lacking complete ferrules using cast precious metal alloy post-and-cores and knife-edged crowns: A retrospective clinical study.

STATEMENT OF PROBLEM: While the presence of a ferrule has been reported to be essential for post-and-core restorations, many extensively damaged teeth lack complete ferrules. The outcome of post-and-core restorations for these teeth remains uncertain. PURPOSE: The purpose of this retrospective clinical study was to assess the outcome of cast alloy post-and-cores and knife-edged crowns for the restoration of teeth lacking complete ferrules. MATERIAL AND METHODS: A total of 106 participants with endodontically treated teeth with 2 or fewer walls with ferrules who had received cast precious metal alloy post-and-cores along with knife-edged crowns between 2013 and 2022 were recalled for a clinical examination. The minimum follow-up time was 5 months after restoration, and restoration failure and the periodontal status difference between restored teeth and reference teeth were determined. Kaplan-Meier analysis was performed to obtain success curves. The influence of age, sex, jaw position, tooth type, and antagonistic dentition upon the success function was analyzed with the log-rank or Breslow test (α=.05). RESULTS: A total of 100 participants with 130 restorations were studied. The success rate of the restorations was 93.85% in a mean ±standard deviation period of 48.3 ±26.1 months. The estimated 5-year cumulative success probability was 91.61%. No significant effect on the success of restorations was found regarding age, sex, jaw position, tooth type, or antagonistic dentition (P>.05). The main failure types were post debonding, root fracture, and apical periodontitis. No statistical difference in tooth mobility (Z=-1.265, P=.206) was found between the restored and the reference teeth, but the plaque index and calculus index of the restored teeth were significantly lower than of the reference teeth (Z=-7.216, P<.001; Z=-7.044, P<.001). Teeth that had received cast post-and-cores and knife-edged crowns were found to have no significant correlation with periodontal disease (χ²=1.131, P=.288) or bleeding on probing (χ²=3.436, P=.064). CONCLUSIONS: The clinical outcomes for the restoration of teeth with 2 or fewer walls with ferrules using cast precious metal alloy post-and-cores and knife-edged crowns were favorable, exhibiting a high 5-year cumulative success probability and no increased periodontal health risk.

Clinical outcomes of self-glazed zirconia veneers produced by 3D gel deposition: a retrospective study.

BACKGROUND: Self-glazed zirconia (SZ) restorations are made by a novel additive three-dimensional gel deposition approach, which are suitable for a straightforward completely digital workflow. SZ has recently been used as minimally invasive veneer, but its clinical outcomes have not been clarified yet. This study aimed to evaluate the preliminary clinical outcomes of SZ veneers compared with the widely used lithium disilicate glass-ceramic veneers made by either pressing (PG) or milling (MG) process. METHODS: Fifty-six patients treated with SZ, PG, and MG veneers by 2 specialists between June 2018 and October 2022 were identified. Patients were recalled for follow-up at least 1 year after restoration. Clinical outcomes were assessed by 2 independent evaluators according to the modified United States Public Health Service (USPHS) criteria. Overall patient satisfaction was assessed using visual analogue scale (VAS), and analyzed by one-way ANOVA. Chi-square test was applied to compare the difference in the success and survival rates among the 3 groups. RESULTS: A total of 51 patients restored with 45 SZ, 40 PG, and 41 MG veneers completed the study, with a patient dropout rate of 8.9%. Mean and standard deviation of follow-up period was 35.0 ± 14.7 months. All restorations performed well at baseline, except for 2 SZ veneers with mismatched color (rated Bravo). During follow-up, marginal discrepancy (rated Bravo) was found in 4 MG veneers and 1 PG veneer, and partially fractured (rated Charlie) was found in another 2 PG veneers. The survival rate of SZ, PG, and MG veneers was 100%, 95%, and 100%, with a success rate of 95.56%, 92.50%, and 90.24%, respectively, none of which were significantly different (p = 0.099 and 0.628, respectively). The mean VAS score of SZ, PG, and MG was 95.00 ± 1.57, 93.93 ± 2.40, and 94.89 ± 2.00 respectively, without significant difference (p > 0.05). CONCLUSION: SZ veneers exhibited comparable preliminary clinical outcomes to PG and MG veneers, which could be considered as a feasible option for minimally invasive restorative treatment.

Turnover behavior and intention among dentists and medical doctors: a cross-sectional study in China.

BACKGROUND: Retention of doctors is a global challenge and doctors working in different departments may face different problems. The study aimed to explore the turnover behavior and intention and correlated factors among Chinese dentists and medical doctors in other clinical fields. METHODS: A cross-sectional study was conducted online in 5 regions of China from March 12th to April 12th, 2020. The questionnaire included 3 parts, socio-demographic characteristics, turnover behavior and intention, and concerns about work-related factors. Chi-square test and/or Wilcoxon Mann-Whitney test were applied for comparison, and binary logistic regression was used for finding the factors. RESULTS: A total of 2428 eligible questionnaire were received, comprising 1954 responses from dentists and 474 from medical doctors. Rates of turnover behavior among dentists and medical doctors were 2.87% and 6.96%, respectively. Similarly, rates of turnover intention were 51.79% among dentists and 71.20% among medical doctors. Educational level was negatively correlated with turnover behavior of both medical doctors and dentists, and concern about salary was a unique negatively correlated factor for dentists. Age was negatively correlated with turnover intention in both medical doctors and dentists. Conversely, concerns about workload and doctor-patient relationship were positively correlated with turnover intention in both groups. Concern about salary was the distinct correlated factor of medical doctors' turnover intention, while gender and annual household income were correlated with turnover intention among dentists. CONCLUSIONS: Low turnover rate but high turnover intention rate was the current status of Chinese doctors' employment. Turnover behavior and intention were more optimistic among dentists than medical doctors. Factors related to turnover behavior and turnover intention were not identical among dentists and medical doctors. Therefore, personalized retention measures were necessary for dentists and medical doctors.

Does fear of infection affect people's dental attendance during COVID-19? A Chinese example to examine the association between COVID anxiety and dental anxiety.

Introduction: Little is known about the psychological and behavioural effect of COVID-19 pandemic on patients and their reaction to dental visiting. Patients may delay attendance due to fears of contracting the corona virus at the dentist. The study aims to confirm the psychometric properties of the two COVID-19 scales and then use dental patient responses to assess the associations between the COVID-19 Anxiety Scale (CAS), dental anxiety (MDAS) and the clinical care COVID-19 Anxiety (CCAS). Methods: A cross-sectional study was conducted among 503 patients visiting a polyclinic of a stomatological hospital in East China in 2020. Patients completed a survey consisting of demographical information, dental attendance, COVID-19 Anxiety Scale, Clinical Care COVID-19 Anxiety Scale and Modified Dental Anxiety Scale. Confirmatory factor analysis was conducted to determine the psychometric characteristics. A further structural model was tested with the combined measurement model and a path analysis was calculated. Results: The sample (n = 503) consisted of more women than men (63% vs. 37%). A fifth of the sample (21%) claimed regular dental attendance and just over a third (35%) reported delaying their dental visit due to the pandemic. Our analysis showed that both CAS and CCAS possessed a unidimensional structure. The MDAS was divided into anticipatory and treatment components as separate latent variables. The anticipatory component (MDAS_A) had some association to CCAS through its expression on treatment dental anxiety (MDAS_T). General anxiety about COVID (CAS) had a direct effect on CCAS. The fit statistics were acceptable [Chi-square = 183.27, df = 68, p < .001; CFI = 0.973; RMSEA = 0.058 (95%CIs: 0.048-0.068)] and the Standardised Root Mean Square Residuals (SRMR) index was 0.041. Discussion: The Clinical Care COVID-19 Anxiety has shown satisfactory psychometric properties. Both dental anxiety and general anxiety about the pandemic have strong associations to patients' fear of contracting corona virus when using dental facilities. Our study has practical implications to help healthcare providers better understand how environmental stressors influence patients' overall concerns on infection risks and appropriate dental treatments during the pandemic.

Artificial intelligence in the diagnosis of dental diseases on panoramic radiographs: a preliminary study.

BACKGROUND: Artificial intelligence (AI) has been introduced to interpret the panoramic radiographs (PRs). The aim of this study was to develop an AI framework to diagnose multiple dental diseases on PRs, and to initially evaluate its performance. METHODS: The AI framework was developed based on 2 deep convolutional neural networks (CNNs), BDU-Net and nnU-Net. 1996 PRs were used for training. Diagnostic evaluation was performed on a separate evaluation dataset including 282 PRs. Sensitivity, specificity, Youden's index, the area under the curve (AUC), and diagnostic time were calculated. Dentists with 3 different levels of seniority (H: high, M: medium, L: low) diagnosed the same evaluation dataset independently. Mann-Whitney U test and Delong test were conducted for statistical analysis (ɑ=0.05). RESULTS: Sensitivity, specificity, and Youden's index of the framework for diagnosing 5 diseases were 0.964, 0.996, 0.960 (impacted teeth), 0.953, 0.998, 0.951 (full crowns), 0.871, 0.999, 0.870 (residual roots), 0.885, 0.994, 0.879 (missing teeth), and 0.554, 0.990, 0.544 (caries), respectively. AUC of the framework for the diseases were 0.980 (95%CI: 0.976-0.983, impacted teeth), 0.975 (95%CI: 0.972-0.978, full crowns), and 0.935 (95%CI: 0.929-0.940, residual roots), 0.939 (95%CI: 0.934-0.944, missing teeth), and 0.772 (95%CI: 0.764-0.781, caries), respectively. AUC of the AI framework was comparable to that of all dentists in diagnosing residual roots (p > 0.05), and its AUC values were similar to (p > 0.05) or better than (p < 0.05) that of M-level dentists for diagnosing 5 diseases. But AUC of the framework was statistically lower than some of H-level dentists for diagnosing impacted teeth, missing teeth, and caries (p < 0.05). The mean diagnostic time of the framework was significantly shorter than that of all dentists (p < 0.001). CONCLUSIONS: The AI framework based on BDU-Net and nnU-Net demonstrated high specificity on diagnosing impacted teeth, full crowns, missing teeth, residual roots, and caries with high efficiency. The clinical feasibility of AI framework was preliminary verified since its performance was similar to or even better than the dentists with 3-10 years of experience. However, the AI framework for caries diagnosis should be improved.

Evaluation of a platform-switched Morse taper connection for all-on-four or six treatment in edentulous or terminal dentition treatment: A retrospective study with 1-8 years of follow-up.

BACKGROUND: The survival rate, marginal bone loss and soft tissue health of the Ankylos implants and the balanced base abutments in all-on-four or six implant restoration of edentulous or terminal dentition patients has not been reported in the clinical research. PURPOSE: This retrospective study aimed to evaluate the Ankylos implants and the balanced base abutments in all-on-four or six implant restoration of edentulous or terminal dentition patients after 1-8 years of follow-up. MATERIALS AND METHODS: A retrospective study was conducted based on the medical records of 33 patients who received all-on-four or six treatments from April 2014 to May 2020. Four radiographic examinations [immediate postoperative (T0), definitive restorations (T1), 1-3 years after prosthetic restorations (T2), and more than 3 years after prosthetic restorations (T3)] were obtained to evaluate vertical bone height (VBH). We also calculated the survival rate and examined the condition of soft tissue with this implant system in edentulous or terminal dentition patients. Three-level linear model analyses were used to explore potential risk factors for VBH changes on the mesial and distal sides. The generalized linear model was used to analyze the influencing factors of BOP and plaque. RESULTS: A total of 218 implants were included in this study. The cumulative survival rate of the implants was 97.25% before the definitive prosthesis, 96.33% within 3 years of follow-up and 95.32% after more than 3 years of follow-up. The mean ± standard deviation (SD) bone losses of the VBH were 0.27 ± 0.05 mm (T1-T3) on the mesial side and 0.49 ± 0.06 mm (T1-T3) on the distal side. During 1-8 years of follow-up, the height and angle of the abutment (p < 0.001), the mandible implant site (p < 0.001), the length of the implant (p = 0.014 < 0.05) and age (p = 0.029 < 0.05) showed statistically significant effects on vertical mesial bone height (VMBH) and vertical distal bone height (VDBH). The risk of BOP among participants who brushed three times a day was lower than those who brushed less than three times. The plaque risk of short abutment height was higher than the long abutment. CONCLUSION: The current study showed that the Ankylos implants with the balanced base abutments in all-on-four or six implants treatment is a viable and predictable option with a high survival rate and low marginal bone loss in edentulous or terminal dentition patients. VBH around the implants was strongly associated with the mandible implant site, abutment height and angle, the length of the implant and age. Moreover, teeth-brushing times and abutment height significantly affect soft tissue health.

Lignocellulosic-Based Nanoparticles with Photoluminescent Properties for Bioimaging.

Natural and renewable resources from plants or animals are an important source of biomaterials due to their biocompatibility and high availability. Lignin is a biopolymer present in the biomass of plants, where it is intertwined and cross-linked with other polymers and macromolecules in the cell walls, generating a lignocellulosic material with potential applications. We have prepared lignocellulosic-based nanoparticles with an average size of 156 nm that exhibit a high photoluminescence signal when excited at 500 nm with emission in the near-infrared (NIR) region at 800 nm. The advantage of these lignocellulosic-based nanoparticles is their natural luminescent properties and their origin from rose biomass waste, which eliminates the need for encapsulation or functionalization of imaging agents. Moreover, the in vitro cell growth inhibition (IC50) of lignocellulosic-based nanoparticles is about 3 mg/mL, and no in vivo toxicity was registered up to 57 mg/kg, which suggests that they are suitable for bioimaging applications. In addition, these nanoparticles can circulate in the blood and are excreted in urine. The combined high luminescence signal in NIR, small size, low in vitro toxicity, low in vivo toxicity, and blood circulation support the potential of lignin-based nanoparticles as a novel bioimaging agent.

Dental caries status and its associated factors among schoolchildren aged 6-8 years in Hangzhou, China: a cross-sectional study.

BACKGROUND: Dental caries prevalence reaches the first peak around 6 years old. It is necessary to take effective measures to prevent and treat caries at this stage. This study investigated the prevalence and associated factors of dental caries among schoolchildren aged 6-8 years in Hangzhou City, China. METHODS: A cross-sectional survey was conducted in Hangzhou from October 2017 to May 2018. Oral health status of schoolchildren in 1st and 2nd grades of primary schools aged 6-8 years was examined by well-trained examiners according to the WHO criteria. Questionnaires about potential caries-related factors were distributed to their parents. ANOVA test and logistic regression were conducted for the statistical analyses (α = 0.05). RESULTS: A total of 7959 pairs of schoolchildren and their parents were invited to participate, and 5595 were included in this study according to the eligible criteria (response rate: 70.3%). The overall prevalence and mean dmft/DMFT of dental caries in the investigated schoolchildren were 52.78% and 2.11. The prevalence and mean dmft/DMFT were 39.05% and 1.63 in the deciduous teeth, while these were 21.45% and 0.48 in the permanent teeth, respectively. For the first permanent molars (FPMs), the rate of fully eruption and pit and fissure sealing (PFS) were 79.09% and 6.60%, respectively. Multiple logistic regression showed that girl (OR = 1.12, 95% CI 1.01-1.25, p < 0.05), seldom or never brush teeth (OR = 2.36, 95% CI 1.08-5.44, p < 0.05), consuming sweet food or drink once or more time a day (OR = 1.14, 95% CI 1.00-1.29, p < 0.05; OR = 1.21, 95% CI 1.07-1.36, p < 0.05), dental visit experiences (OR = 1.58, 95% CI 1.35-1.86, p < 0.001) were positively and no tooth pain in the past 12 months (OR = 0.55, 95% CI 0.38-0.80, p < 0.05) were negatively associated with caries. CONCLUSIONS: Dental caries was prevalent among schoolchildren aged 6-8 years in Hangzhou, and was associated with gender, frequency of toothbrushing, sweet food or drink consuming, tooth pain and dental visit experiences. A large number of fully erupted FPMs did not receive timely PFS.

Adaptation and uniformity of monolithic zirconia crowns fabricated by additive 3-dimensional gel deposition.

STATEMENT OF PROBLEM: A novel monolithic zirconia restoration fabricated by additive 3-dimensional (3D) gel deposition, named as self-glazed zirconia (SGZ), has recently been developed. SGZ crowns exhibit reliable mechanical properties and esthetic appearance, but their adaptation and uniformity are unclear. PURPOSE: The purpose of this in vitro study was to compare the adaptation and uniformity of monolithic zirconia crowns fabricated by additive 3D gel deposition with that of milled zirconia and lithium disilicate crowns. MATERIAL AND METHODS: Ten identical resin abutments were made based on the scanning data of an extracted and prepared human mandibular first molar. Three types of monolithic crowns were then fabricated by using 2 different processes: 3D gel deposition zirconia (SGZ), milled zirconia (ZZ), and milled lithium disilicate (EMX) (n=10) through a completely digital workflow. The nondestructive direct-view technique and replica technique were used to measure the marginal and internal discrepancy values individually. The uniformity index was calculated to describe the uniformity of the internal space. The results were analyzed by using 1-way ANOVA and Kruskal-Wallis statistical tests (α=.05). RESULTS: The marginal discrepancy of EMX exhibited the highest values among the 3 groups (P=.001). The 2 types of zirconia crowns had comparable marginal discrepancy values (P>.05). The internal discrepancy values of SGZ were significantly lower than those of EMX at the occlusal region and of ZZ at all measured locations (P<.05). All 3 types of monolithic crowns showed comparable good uniformity (P=.056). CONCLUSIONS: The marginal and internal adaptations of novel monolithic zirconia crowns were within clinical requirements. Compared with the zirconia and lithium disilicate crowns fabricated by subtractive milling, monolithic zirconia crowns fabricated by additive 3D gel deposition had comparable uniformity and better internal adaptation.

Plaque removal efficacy of a compacted dual-head power toothbrush: A split-mouth randomized clinical trial.

PURPOSE: To evaluate the plaque removal efficacy of a compacted dual-head power toothbrush (DH) in comparison with a single-head power toothbrush (SH). METHODS: 24 healthy university students were included in this split-mouth and single-center clinical trial. The DH and SH were randomly assigned to brush the left/right half mouth in the first visit. Testing time points were 30 and 60 seconds. Additionally, 15 and 45 seconds were set for the DH period. The overall, buccal, lingual, gingival marginal, and proximal plaque scores at different time points were recorded and determined by Rustogi Modification of the Navy Plaque Index. To avoid the influence of the right handedness, subjects were brushed in the second visit after 4 weeks, and the SH and the DH were assigned to the right/left half mouth in an opposite period to that of the first visit. RESULTS: 21 participants completed this study. Overall plaque score reductions of the SH and DH were 29% and 59% (P< 0.05) at 30 seconds, and the reductions were 47% and 77% respectively (P< 0.05) at 60 seconds. Using the DH for 45 seconds reduced significantly more overall, buccal, lingual, and gingival marginal plaque than that of using SH for 60 seconds (P< 0.05). The SH reduced plaque scores significantly less in the right and lower dentitions than left and upper dentitions respectively, while DH reduced comparable plaque scores between these dentitions. The DH is more effective in removing overall, buccal, lingual, gingival marginal, and proximal plaque in healthy university students than the SH, meanwhile DH showed comparable overall plaque reduction rates between different regions of the dentitions. CLINICAL SIGNIFICANCE: This compact dual-head power toothbrush provides a new option to carry out daily plaque control effectively.

Bone morphogenetic protein-2 incorporated calcium phosphate graft promotes peri-implant bone defect healing in dogs: A pilot study.

OBJECTIVES: The evaluation of three different drug delivery modes of bone morphogenetic protein-2 (BMP-2) in healing peri-implant bone defects in beagle dogs. BMP-2 was incorporated in or onto calcium phosphate (CaP) granules in various ways: (i) directly on the outer layer of granules CaP: as an adsorbed depot; (ii) during the entire precipitation process of CaP: an internally incorporated depot; or (iii) during the biomimetic coating precipitation of BMP-2 on the surface of CaP granules: as a coating incorporated depot. MATERIAL AND METHODS: After extraction of the lower molars and wound healing in 6 male beagle dogs, 36 implants were placed (n = 6 animal per group). Peri-implant bone defects were induced. The following treatment groups were evaluated: no treatment; air abrasive surface cleaning (SC) using hydroxyapatite; SC and the subsequent filling of the defect with CaP without BMP-2; SC plus the subsequent filling of the defect with CaP adsorbed BMP-2; SC plus the subsequent filling of the defect with CaP internally incorporated BMP-2; SC plus the subsequent filling of the defect with CaP coating incorporated BMP-2. Histological and histomorphometric analyses were carried out to quantify and compare the changes in bone tissue surrounding the treated implants. RESULTS: In Group 1 with no treatment, four implants were lost. Group 5 with the SC and the subsequent filling of the defect with internally incorporated BMP-2 biomimetically prepared CaP (BioCaP), whereby the BMP-2 is incorporated in the entire volume of all BioCaP particles, showed overall the best results to regenerate bone around the implants. CONCLUSION: This study concluded that the group treated with SC plus the subsequent filling of the defect with CaP BMP-2 internally incorporated BMP-2, whereby BMP-2 has been incorporated in the entire volume of all CaP particles, showed overall the best results when aiming to regenerate bone around the implants.

Effects of Grinding and Polishing on Surface Characteristics of Monolithic Zirconia Fabricated by Different Manufacturing Processes: Wet Deposition and Dry Milling.

PURPOSE: To evaluate the effects of grinding and polishing on surface characteristics of monolithic zirconia fabricated by two different manufacturing processes. MATERIALS AND METHODS: Two types of monolithic zirconia specimens, self-glazed zirconia (SZ) and conventional zirconia (CZ), were fabricated by wet deposition and dry milling, respectively. The specimens were randomly assigned into 4 groups (n = 10): as-sintered, ground, polished with a special zirconia polishing kit, and polished with a general-purpose ceramic polishing kit. Surface morphology and roughness (Ra ) were characterized, followed by one-way ANOVA analysis (α = 0.05). RESULTS: The as-sintered SZ exhibited a smooth surface with obvious different morphologies compared with the as-sintered CZ (Ra : 0.26 ± 0.05 µm versus 0.33 ± 0.10 µm). Ra of the ground SZ was significantly higher than that of the as-sintered SZ (p < 0.001) and the ground CZ (p = 0.011). For both SZ and CZ, Ra decreased significantly after polishing (p < 0.001), and there was no significant difference between the two groups with different polishing kits (SZ- p = 0.144; CZ- p = 0.322). Surface morphologies of SZ and CZ became similar after grinding and polishing. CONCLUSIONS: Monolithic zirconia SZ fabricated by wet deposition exhibited a smooth surface with specific patterns compared to the dry milled CZ. Grinding significantly changed the surface morphology of SZ and increased surface roughness of both zirconia specimens, which can be improved by polishing without being influenced by polishing kit selection.

Three-dimensional fit of self-glazed zirconia monolithic crowns fabricated by wet deposition.

This study evaluated the 3-dimensional (3D) fit of self-glazed zirconia monolithic crowns fabricated by wet deposition, in comparison with milled zirconia and lithium disilicate monolithic crowns. Dual-scan protocol was used to assess the fit of crowns. Root mean squares (RMS) and uniformity index (UI) were calculated to describe the gap size and uniformity. The self-glazed zirconia crowns had significantly lower RMS values for the gaps at axial wall and transition regions than the milled zirconia crowns, and for the gaps at occlusal region than both milled crowns. All 3 types of crowns had comparable RMS values for the gaps at marginal and chamfer regions and comparable UI values for both marginal and internal gaps. The 3D fit of the self-glazed zirconia monolithic crowns was clinically acceptable and they exhibited better fit at occlusal region than the milled crowns.

Retrospective clinical study of monolithic zirconia crowns fabricated with a straightforward completely digital workflow.

STATEMENT OF PROBLEM: Current computer-aided design and computer-aided manufacturing (CAD-CAM) technology has digitalized some traditional prosthodontic processes, but manual interventions are still needed for both clinical and dental laboratory procedures, and improved digital workflows are required. PURPOSE: The purpose of this retrospective clinical study was to develop a straightforward completely digital workflow to fabricate monolithic zirconia crowns and evaluate clinical efficiency and prosthetic outcomes. MATERIAL AND METHODS: Self-glazed zirconia crowns (N=229) were placed in 177 participants between 2016 and 2019 with a completely digital workflow. The extent of clinical adjustment needed for each crown was recorded and then divided into 3 categories: zero adjustment, minimal adjustment, and unacceptable. Color match and marginal adaption were evaluated according to the modified US Public Health Service (USPHS) criteria. RESULTS: A total of 213 (93.0%) crowns required zero adjustment during clinical evaluation, 11 (4.8%) needed minimal adjustment, and 5 (2.2%) were deemed unacceptable since they could not meet the clinical requirements through adjustment. Except for the unacceptable crowns, the marginal adaption of the remaining 224 crowns was rated as Alfa and the color match as Alfa (91.5%), Bravo (6.3%), and Charlie (2.2%). CONCLUSIONS: The self-glazed monolithic zirconia crowns fabricated with the completely digital workflow provided efficient and satisfactory clinical performance.

Vertical bone augmentation with simultaneous implantation using deproteinized bovine bone block functionalized with a slow delivery of BMP-2.

OBJECTIVE: We hypothesized that a biomimetic calcium phosphate (CaP) coating which incorporates morphogenetic protein 2 (BMP-2) on the deproteinized bovine bone (DBB) blocks could be used to enhance the vertical alveolar ridge augmentation for the one-stage onlay surgery with simultaneous implants insertion. We aimed to test this hypothesis in vivo. MATERIAL AND METHODS: Beagles dogs were used for the study (n = 6 specimens per group). One month after building the edentulous animal model, 4 mm vertical alveolar bone loss were surgically created and four groups of blocks (W × L × H: 7 mm × 10 mm × 4 mm) were randomly fixed onto the reduced alveolar ridge by implants: (a) DBB blocks alone (negative control group); (b) DBB blocks with superficial adsorption of 50 µg BMP-2 (ad.BMP-2 group); (c) DBB blocks coated by biomimetic CaP coating which incorporates 50 µg BMP-2 (inc.BMP-2 group); and (d) autologous bone blocks (positive control group). After 3 months of healing, samples were harvested for micro-CT and histomorphometric analyses. RESULTS: In histomorphometry, the inc.BMP-2 group showed a significantly thicker (coronal-apically) and wider (buccal-lingually) augmented bone area, better bone-to-implant contact than the negative control group. In both the micro-CT and histomorphometry, the inc.BMP-2 group showed more mineralized tissue than the negative control group and the inc.BMP-2 group also showed significantly more newly formed bone and residual grafts than the negative control group in the upper half of the blocks. In micro-CT, the inc.BMP-2 group showed significantly more bone-to-graft contact percentage than the ad.BMP-2 group. In both micro-CT and histomorphometry, the inc.BMP-2 group showed significantly more percentage of mineralized tissue than the ad.BMP-2 group. No significant differences were found between the inc.BMP-2 group and the positive control group either in micro-CT or in histomorphometry. CONCLUSIONS: The DBB blocks with coating-delivered BMP-2 significantly enhanced the efficacy of vertical alveolar bone augmentation, compared with the unloaded blocks and blocks with adsorbed BMP-2, in the one-stage onlay surgery with simultaneous implant insertion.

Bone Tissue Responses to Zirconia Implants Modified by Biomimetic Coating Incorporated with BMP-2.

This study aimed to histologically investigate the bone tissue response to zirconia implants functionalized with a biomimetic calcium phosphate (CaP) coating incorporated with bone morphogenetic protein-2 (BMP-2). Zirconia implants coated with biomimetic CaP were prepared with and without BMP-2. Untreated zirconia implants served as a control. These three groups of implants were placed randomly in the mandibles of six beagle dogs (n = 6). Three months later, samples were harvested for histomorphometric analysis. The present study showed that the application of a biomimetic CaP coating incorporated with BMP-2 enhanced the peri-implant osteogenesis for zirconia implants.

Peri-implantitis Induced by Stainless Steel Ligature in Beagle Dogs.

The purpose of this study was to develop a new method for a peri-implantitis model in beagle dogs in which a stainless steel ligature (SSL) was used independently. A total of 36 Straumann dental implants were placed in six beagle dogs 1 month after all mandibular premolars were extracted. After 3 months, SSLs were placed in a submarginal position on the implants to induce peri-implantitis and were not replaced during the 12-week tissue breakdown period. Inducing peri-implantitis in the beagles with an SSL is a rapid, effective, and simple method.